[Signmaker]

If you've bought the standard Chinese style "chiller" to keep your tube temperature down prepare to chuck it in the bin as soon as you unpack it.

Chinese "chiller" units are shockingly rubbish.... inside the average "chiller" you will find a couple of aluminium coils and a fan... that's it. There is NO chilling mechanism inside the casing... just an oversize electric fan pulling ambient temperature air over a couple of teeny weeny heat sinks. Needless to say these "chillers" don't chill and are hopeless at maintaining a precise coolant temperature.

In the UK these chillers keep the coolant cool for about 10 minutes... then the temperature slowly climbs to an unacceptable level. In Greece during the summer I think you'll get about 4 minutes worth of "cooling".

[fantasy2]

well.. that depends on the chiller. The company that sold the laser to me advised me not to buy the standard chiller but to do an upgrade. It was not only more expensive but it's also a real chiller. The standard ones just have a cooling fin and pump the water around and indeed, that's not sufficient.

[Litografa]

Fantasy2 - is not a secret - what is price of UPGRADED chiller? The best price I found in China was $1200. Work perfect but delivery/customs add $600 more

[neoman1]

Hi guys,

Yesterday I received my new LG900N Gweike laser. I will set it up this weekend and I have a question to ask you:

Is it better to fill the water cooling circuit with paraflu (chilling fluid for car cooling circuit and more) or just plain water?

I hope everything goes on schedule tomorrow!

Thanks

[Litografa]

This question was discussed here few times with different opinions. My is - distilled water!

[zax15uk]

I agree, DI water is best. You can add a small amount of Propylene glycol coolant (1 in 20) or as I prefer HydrX™ (anti-fungal).

Additives reduce the efficiency of the coolant and laser, but increase the working life before you need to flush and replace the coolant.

Zax.

[DaveDoesIT]

I understand that I should never cut PVC or Teflon plastics! I suppose that I can cut celluloids.

There is a lot of misinformation about cutting PVC. PVC when heated will give off a Chloride gas when mixed with moisture in the air it can form Hydrocloric Acid (HCL). This can deposit on steel parts of the machine and lead to rust. OK, so far so bad. The reality is that if you have a good extraction system and/or low humidity where you live, the HCL is not a problem. I regularly cut PVC pipe and have not had a single problem but I do have a 700cfm extraction system that vents to the outside. The amounts of HCL available is minuscule but it would be very unwise to cut PVC without a good extraction system. As to Celluloid, it is extremely flammable and will burn instantly. Definitely NOT a laserable material.

[dhruv9]

Hi Mike.

Could Rohacell (RC 71 IG) Foam be cut using CNC/VMC using typical tools rather than going for laser cut or other technology?

I want to make 10mm diameter cylinders of the same material and further processing.

Please reply at [email protected]

Cheers
Manish

[Litografa]

Manish, try to test laser for cutting Rohacell. Looks like suitable material for lasering. May be you will need use of nitrogen instead air in air assist to achieve better quality

[Mike F]

I replied privately to Manish saying that Rohacell cuts beautifully with a laser. I have cut up to 25mm thick Rohacell and at that thickness it is best done in two or three passes on reduced power rather than trying to blast through in one pass. Although it did cut in one pass, the cut had quite a taper on it due to melt back. Thin sheet cuts so easily and at very low power.

Mike

[dhruv9]

Cheers to both of you guys. Your guidance would be useful for us. Only problem with laser cutting would be at the moment is that we're not equipped with one, only having traditional CNC and VMCs.

Btw where in Lancashire you're from Mike? I've lived in Blackburn for couple of years. Now I'm in India though for promoting and developing a manufacturing firm.

Manish

[Mike F]

Hi Manish,

Over the other side, in West Lancashire, just outside the market town of Ormskirk.

One of the great things about using the laser for cutting Rohacell is there is very little waste and no dust!! Having said that, I probably still use my CNC mill for the majority of Rohacell work as much of it is 3D stuff.

All the best,

Mike

[ksamay]

Hi mike,

firstly thank you so much for creating this thread . It was of huge help for a person who is just looking at buying a laser machine from china.

Could you tell me the benefit of a honey comb bed and how much extra did it cost you ?

Also , Does any body know if i need to buy a chiller for a 80W laser and is a $300 chiller a real chiller or as others have said " just a cheap Heatsink with fans " ?

[Mike F]

Hi ksamay,

A honeycomb bed is very useful if you intend cutting very small parts. Without it, the parts would fall through the support rails. They don't come cheap and I think mine was an extra £100 GBP but it was essential for my work. If you haggle with the supplier, they might include one at no extra cost. Although I paid for mine, I did get one or two other extras like the rotary axis for free.

My laser is an 80W machine and I don't have a chiller and have never had the need for one. Mind you, I don't run mine for long periods at a time so it probably does not get hot enough to warrant a chiller. Provided you have a large enough reservoir for the water and a good flow rate, it should be fine without. It also depends on what you intend to cut or rather the power you intend to cut at. I have never yet had the need to use 100% power.

Hope this helps,

Mike

[ksamay]

thanks mike. i will most probably go with the honey comb table.

i am still confused about the chiller as i might need to run my laser at near full power as i intend to majorly use it for cutting acrylic sheets ( upto 15-17mm thick ) . But what i confused at more is that should i buy the one Jcut is planning to supply or find one here locally . ( i read some bad reviews about chinese chillers )

Also, do you have any idea on how an auto focus system works and is it needed ? Did you get it ? is it useful for someone who does not want to engrave but just cut. Do you need to focus the laser every time you want to cut material of difference thickness ?

Thanks in advance,
samay

[cxcnc]

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[Mike F]

Hi Samay,

I'm not sure how the auto focus works and no, I did not get it on my machine. It really is not a problem re-focussing for different thicknesses of material. It is simply a turn of a thumb screw and the distance is set with an acrylic template that came with the machine.

I'm afraid I cannot help with information on the chiller but I too have seen the comments about Chinese chillers. However, you are in India and I am in the North of England and I should imagine there is quite a bit of difference in ambient temperature and a chiller may be more of a necessity. It is probably worth posting a question in your own thread in the laser forum where there will be people far better informed than me, rather than here.

All the best,

Mike

[digger0902]

Mike,

I see that you have tried this process- can you give me some further info please. we are trying to cut some deep holes into a rohacell cored aerofoil wing section.

hope to hear back from you later,
my e-mail is [email protected]

Graeme

[Mike F]

Hi Graeme,

What thickness and density is the Rohacell you are trying to cut?

I managed to cut through 30mm of 31 grade Rohacell with the edges remaining pretty square. I did this by reducing the power considerably and making multiple passes. I did not find the need to raise the bed during the cut and was surprised that there was no need to re-focus the laser despite thickness of cut.

Do I take it from your email address that you are working for McLaren? Do let me know if they have room for a not too old codger who is into composites

Cheers,

Mike

[digger0902]

Mike,

Hello, the material is Rohacel 51 and we are trying to cut a dia 8,0 mm hole which would be 350mm deep into the section , however reading your reply this probably is not the process which is most likely to succeed - due to the hole depth etc and the fact that it is closed on all surfaces.
If you have any other suggestions to achieve this reqt which do not involve a machine tool to drill / bore this hole detail I would be interested to hear about them.
The part already has a CFRP skin all around the outside and this a 'post-machining' machining reqt for an existing component- ie not made from new.

thanks,

Graeme